Insulator



E. BURKE INSULATOR April 7, 1931.

Filed Feb. 7, 1927 2o and tensile strength 40 tensile strength.

Patented Apr. 7, 1931' UNITED STATES vParraN'r' OFFICE ummm) BURKE, orIPOBTLAND,

MAINE, ASSIGNOB TO BROWN COMPANY, 01' PORT- LAND, MAINE, A CORPORATIONOF MAINE INSULATOR Application led February 1 1927. Serial No. 168,538.

My present invention relates to insulators and is of particularlimportance in connection with insulators for high tension installation.Such and are of such a fragile nature that they1 are frequently broken1n shipping and handling or are peculiarly objects of vandalism as bysniping. rlhis all contributes to a w very heavy installation and upkeepcost and to great trouble and annoyance in maintaining eiiciency on thelines. v

It has been proposed to make composition insulators of less expensivematerial and is some of the smaller and simpler types of insulators havebeen so produced. The problem, however, oi' producing a suitableinsulator for high tension lines and one capable of being produced withsuiiicient resistance has not as far as I know been solved. The problemincludes that of producing insulator structures of a tensile strengthsufficient to withstand many thousand pounds and at the same time beingable to withstand the sparking and arcing effects of the highestvoltages.l

Considering iirst the material phase of my invention I secure a tensilevariant while preserving a substantially homogeneous material in twoforms each old in itself and bothv heretofore used together but I usethem in a new relation and according to a new concept of theirpotentialities.

Briey, this aspect of myk invention re lates tothe use of a fibrousmaterial in two forms-both permeable by a dielectric binder butdifferentiated as to permeability and The combining possibilities givein this art that factor much needed and long sought by which commercialsuccess may be attained. A

In dealing with my other factor (structural) I provide a stem member ofgeneral insulators as are at present 5 used for this work are enormouslyexpensive dielectric strength. As herein-v 30 after pointed out I effectthis by the use of construction and ca able of being manufactured fromsuch a bre mixture 1n commercial lengths. i

By combining with v'this unitary elements,

` say of the petticoattype, I am able to produce insulators varying'from the single unit type to those o f maximum total distances capableof insulating against the highest voltages.

For convenience of illustrative reference, I

have selected certain well known types of v insulators and have shown inthe accompanying drawings embodiments in accordance with an exteriorthread and the petticoat units 2 are threaded thereon preferably beingpinned as at P by wooden pegs as indicated 1n Fig. 2.

Such an insulator as shown in Fig. 1 may have the usual upper eyedconnectionscrewed on to the end of the tube and a lower clevisconnection screwed on the other end as indicated at 4. The tubularmember. l is preferably filled with a high melting point pitch, asindicated at 5. Any desirable pitch or asphaltic material may be usedfor this purpose, as for example gilsonite.

.Where the central stem is to be used in the general pin type ofinsulator I provide as in Fig. 3, a stem l1 threaded as lefore butturned so as to give a butt 12 in which is formed a threaded socket 6corresponding to the usual construction of such insulators. Such aninsulator, I have illustrated in Fig. 3, has its terminal 7 providedwith cable notches and grooves 71 and 72, respectively. In the formshown in Fig. 3, the petticoat units 21 are provided with short necks 22by which the units are spaced from each other.

In Fig. 4 I have shown a convenient structure in the manufacture ofstems for insulator purposes. In this drawing I have indicated thetubular stem b 1. This may be a piece of bre tubing which can beproduced in stock lengths and sizes. On the end of such a section 1 Islip a short section 10 cut from a tubing having an internal diametersubstantially fitting the external diameter of the tube 1. This ring 10is preferably pinned as at P by wooden pins thus forming on the tube 1 ashoulder for carrying any suitable terminal member as 9 having engagingarms or points 8. The pins P are preferably of wood as such pins arecapable of receiving waterproofing and dielectric impregnation.

In such structures it is to be noted that there are two main members,each of which must be of high dielectric strength but when considered asseparate elements only one need be of considera le tensile strength.

This apparently has been one of the failures of previous conceptsrelating to composition insulators. One of thev roblems involved wasthat of providing su stantial homogeneity throughout the'mass of thematerial from which the insulator is formed. This is important as amatter of securing high dielectric strength and is also important as amatter of ultimate bonding or consolidationof the separate members so asto secure a substantial unification.

veloped stem member, stem of substantially the same material as theflange or petticoat portions but of a much higher tensile strength andone capable of being turned or threaded or otherwise worked on to getsuch mechanical assembly as seemed desirable.

I therefore preferably take two classes of the same material, as forexample long wood fibre and fine sawdust or Wood flour.' I find itpreferable to have these of generally the same origin, although it isstitute fibre of proper length of other origin than a Woody origin, asfor example leather bre or even such vegetable bres as cotton. While thewood pulp is preferable for many reasons, there might be adulteration orsubstitution by the use of infusorial earths, cork finely groundclinkers or a great variety of other materials. I mention these in orderthat there may be no misunderstanding as to the scope of my invention,but on account of the inexpensive character of woody matters and theirgeneral availability, such seem to me at present to be logical materialsfor commercial roduction.

In preparing such materials I utilize-the t-wo forms `generally asfollows. For my Having thereforeA understood the possibilities of aspecially defmy concept was of a` possible to substem mixture I usepreferably a long strong fibre such as the best quality of s ruce andpreferably a selected fibre. Such bre takes a hi h impregnation and whenmixed w1th Wood Hour, which is even more easily impregnated, I am ableto get a stem mlxture of very great strength. The amount of the longlibre used merely depends on the ult1- mate strength of the stemrequired and the mixture may be infinitely varied from a low percentageof long fibre to an excluslve use of long fibre which makes a materialof very great tensile strength. Such a stem is capable of being turnedand threaded as indicated 1n the drawings and when producedin tubularform is capable not only of fibre impregnation but of secondaryimpregnations externally and internally and may then be filled with afused or melted core of the same dip electric or any variant desired. Inmaking the flange or petticoat members Where the tensile strength is notneeded, the fibre may be omitted and the wood flour or like materialimpregnated or moulded rapidly and shaped.

The insulator is then assembled in its several parts and preferablydipped 1n a moulten bath of high'melting point pitch or mixture. Such acoating not only completes the assembly and unifies the parts, but byreason of its impregnation of all cracks or exposed surfaces resultingfrom manufacture gives the resultant article a hi h fnlsh, weatherresistant surface, and ma es of the assembly a unit of very highelectrical resistance.

The stem principle as applied to such structures makes possible a veryextended total distance of insulation and makes possible a very ra idassembly of elementary parts into a variety of insulators each whencompleted constituting substantially a d1- electric entirety.v

The filling as indicated at 5 not only makes possible the use of thetubular stem with all its manufacturin advantages, but actually makesout of t at stem a member of greater insulating value which in itselfwould be important apart from the strength and economy gained by the useof the tubular principle for the stem.

While applicant has only attempted to show two general types ofinsulators, it will be understood that most of the usual types anddesigns of insulators can be made in accordance with my invention andthat such variations in design and other variations in details ofstructure and assembly are all understood to be within the purview ofhis invention as defined in What I therefore claim and desire to secureby Letters Patent is 1.. In an impregnated insulator, a stem membercomposed of long wood libre and a comminuted absorbent filler, and aflan e member having a greater amount of said a the appended claims.V

sorbent ller and a lesser amount of long fibre, and a non-conductivecore sealed within said stem..

2. In an impregnated insulator, a. stem member composed of lon wood breand a comminuted absorbent er, and a Han e member having a greateramount of absor ent ller and a lesser amount of said long fibre.

In testimon whereof I ax m si attire.

y EDMUND

